Increase In Adsorbate Concentration Research Articles

Dry fruit shell‐derived biochar increases biosorption potential and detoxification of organic pollutants for land safety

AbstractThe increase in water pollution and land degradation ultimately reduces the supply of clean water for the growing population. Biochar produced from dry fruit shells is an effective adsorbent for organic pollutants. It can help reduce soil contamination and water pollution, making it an important option for land safety. For this experiment, dry fruit shell biochar was produced and activated chemically with 1 M KOH to increase the pollutants' removal efficiency. The efficiency of biochar as an adsorber of pollutants was assessed by characterizations of scanning electron microscope, Fourier transform infrared, and X‐ray diffraction (XRD) techniques. The peak of almond shell biochar was observed between 1033 and 1068 cm−1, while in pistachio, it was observed at 1458–1446 cm−1. Data extracted from XRD showed that most peaks were shifted after activation. For example, in walnut shell biochar, the peak shifted from 11° to 18° after biochar activation. The highest pollutant removal efficiency, such as 92%, 90%, and 87%, was observed in walnut shell biochar at 1, 2, and 3 mLL−1 adsorbate concentration, respectively. Pistachio shell biochar was most effective in the presence of the chemical activator to remove toluene and phenol organic contaminants. An increase in adsorbate concentration decreased the removal efficiency from 50% to 46% in activated almond shell biochar, 58% to 55% in activated pistachio shell biochar, and 55% to 54% in activated walnut shell biochar by 1 gL−1 of adsorbent. Kinetic and equilibrium data with different applied models established that the adsorption process was favorable, and models were fitted to the experimental setup. Biochar prepared from different dry fruit shells and their optimum activation can be used as bio‐sorbent for pollutants' removal and hence improved land development for agriculture and other industrial purposes.

Adsorptive removal of crystal violet dye by Azadirachta indica (neem) sawdust: A low-cost bio-sorbent

The potentiality of Azadirachta indica sawdust as a cost-effective natural adsorbent for adsorptive elimination of a cationic dye crystal violet from aqueous emulsion was investigated. Because sawdust is plentiful and low-cost by-product. Additionally, sawdust can be composted to replace the regeneration stage that other adsorbents like activated carbon requires. Kinetic and isotherm analyses were conducted under variable experimental conditions including adsorbent dose, dye concentration, contact time, pH, and temperature. A maximum adsorption capacity of 8.264 mgg−1 was obtained at optimized conditions of 2.5 gl−1, 100 mgl−1 30 min, 6, and 25 °C for adsorbent dose, adsorbate, contact time, pH and temperature. The nature of any probable interaction between adsorbent and crystal violet was analyzed by FTIR technique, to investigate the type of functional groups in saw dust responsible for dye binding process. The FTIR studies showed the existence of C-H, C=O, C-O, C=C, O-H, C-N, -COO- and Si-O functional groups. It was noted that the sorption kinetics followed a pseudo-second order kinetic model after the sorption was examined using pseudo-first and pseudo-second order kinetic models. The magnitude of dye removal increased with increase of adsorbent dose and slightly decreased with increase in adsorbate concentration. Up to 45 °C temperature, there was no significant impact on sorption only 2–5% higher than the 25 °C and 35 °C treatments. The Langmuir isotherm model provided a good representation of the equilibrium data in aqueous solutions. The adsorption capability of crystal violet onto the sawdust of Azadirachta indica was found to be as high as 8.278 mgg−1, at pH 6.0, temperature 25 °C, and at equilibrium time of 60 min after applying Langmuir isotherm equation. Azadirachta indica sawdust seems to be a very promising adsorbent for the removal of crystal violet from aqueous solution.

Comparative adsorption of emerging contaminants in water by functional designed magnetic poly(N-isopropylacrylamide)/chitosan hydrogels

The magnetic poly(N-isopropylacrylamide)/chitosan hydrogel with interpenetrating network (IPN) structure was designed based on the functional groups of targeted emerging contaminants, represented by hydrophilic sulfamethoxazole (SMZ) and hydrophobic bisphenol A (BPA). The average particle size, specific surface area, and total pore volume of the hydrogel were turned out to be 103.7 μm, 60.70 m2/g and 0.0672 cm3/g, respectively. Adsorption results indicated that the maximum adsorption capacity occurred at the pH where SMZ was anionic and BPA was uncharged. When the adsorption temperature increased from 25 °C to 35 °C, the amount of adsorbed SMZ hardly changed, but that of BPA increased by two times. The adsorption capacity of the binary system (i.e., with both SMZ and BPA) was almost the same as that of the single system, indicating that simultaneous adsorption of SMZ and BPA was achieved. The adsorption equilibrium was reached quickly (within 5 min) for both SMZ and BPA. For adsorption isotherm, the Freundlich model fitted well for SMZ at 25, 35 and 45 °C. However, the adsorption of BPA exhibited the sigmoidally shaped isotherm at 25 °C with the Slips model fitting well, and both the Freundlich isotherm and the Slips isotherm fitted the data well at 35 °C and 45 °C, suggesting that the adsorption force was initially weak but greatly enhanced with an increase in adsorbate concentration or ambient temperature. The main adsorption mechanism was inferred to be electrostatic interactions for SMZ, and hydrophobic interactions as well as hydrogen bonding for BPA. The hydrogel adsorbent maintained favorable adsorption capacity for BPA after five adsorption-desorption cycles. These findings may provide a strategy for designing high performance adsorbents that can remove both hydrophilic and hydrophobic organic contaminants in the aquatic environment.

Arsenic Removal by Using Low Cost Non-conventional (NLP, PLP, ALP) Adsorbents

Abstract In present study, Azadirachta indica (neem leaves), Ficus religiosa (peepal leaves), Emblica officinalis (amla leaves) used as adsorbent. Batch experiments were conducted to study the adsorption behaviour. The material was characterized by FTIR, XRD, TGA-DTA, and SEM-EDS. The extent of arsenic removal capacity was tested by the material by varying the solution parameters like adsorbent dose, adsorbate concentration and pH of the solution, contact time and temperature. The amount of arsenic adsorption increases with the increase of adsorbent concentration which indicates that adsorption depends upon the availability of active sites for arsenic. The experimental data were correlated reasonably well by Freundlich adsorption isotherm. The optimum conditions for the removal of arsenic from water are initial concentration: 0.1 mg/L, adsorbent dose: 1 g/50 mL, pH: 6.0, temperature 50oC±2oC, contact time: 30 min. and shaking time: 1 h is worked out. Increasing order of arsenic adsorption on leaf powders was as follows: NLP > ALP > PLP. It can therefore, be potentially applied for the treatment of water contaminated by arsenate. Keywords: Adsorption; low cost adsorbent; Arsenic concentration; Water treatment Cite this Article Shikha Saxena, Nisha Singh, Nidhi Jain, Arsenic Removal by Using Low Cost Nonconventional (NLP, PLP, ALP) Adsorbents Journal of Modern Chemistry & Chemical Technology . 2018; 9(3): 29–39p.

A study of kinetics and thermodynamics of methylene blue adsorption onto the Yellow River bottom sediment

AbstractIn this paper, the adsorption process and kinetics of methylene blue onto the Yellow River bottom sediment was investigated. It was found that the equilibrium data fitted well to the Langmuir, Freundlich, Toth and Redlich‐Peterson model, with the Langmuir model showing the best fitting result compared to others. The adsorption process attained equilibrium within 60 min, and the adsorption capacity of Yellow River sediment increased with the increase in adsorbent concentration, temperature, and NaNO3 concentration. The adsorption capacity of the Yellow River sediment increases as the adsorbent pH decreases to a certain value and further decreasing the pH value can lead to decreasing adsorption capacity. Moreover, the presence of humic acid in natural concentration range had a minor influence on the adsorption quantity of the Yellow River sediment. Therefore, the Yellow River sediment, an easily available material, can be used for methylene blue removal in wastewater treatment processes.

Hydrophobic modification of bagasse cellulose fibers with cationic latex: Adsorption kinetics and mechanism

The modification of the bagasse cellulose fiber by the adsorption of cationic poly latex with core–shell structure on fiber surfaces was conducted in attempt to enhance the interfacial compatibility between hydrophilic fibers and the hydrophobic substrates for various applications. A two-step semi-batch emulsion polymerization was employed for constructing core–shell latex. TEM and dynamic light scattering (DLS) analysis indicated that the core–shell latex possessed a broad particles size distribution, which led to the adsorption of the latex on fiber proceeding via two-stage equilibrium mainly due to the effect of latex particle size. The pseudo-first-order kinetic model was appropriate for the description of the kinetics of the first stage equilibrium at high latex concentration and the entire adsorption process at low concentration. In contrast, the pseudo-second-order kinetic model fitted the second equilibrium at high latex concentration well. The activation energy calculated suggested that the number of activated molecules was increased as the increase of adsorbent concentration, which might change the dominant adsorption mechanism. This also addressed the reasons for the abnormal adsorption behavior with the extra-added emulsifier. In addition, the surface property of the modified cellulose fibers was also investigated via contact angle measurements. The results proved that the cellulose fiber modified with the latex became hydrophobic, allowing the as-modified cellulose to be potential reinforcements for biocomposite. Finally, the adsorption mechanism was proposed according to the adsorption process mainly governed by electrostatic interactions, hydrogen bond, π–π stack and chain entanglement.

A comparative study for the removal of aniline from aqueous solutions using modified bentonite and activated carbon

AbstractThis study was aimed to explore the potential of modified bentonite as low-cost adsorbent for the adsorption of aniline from aqueous solution. Natural bentonite was modified with hexadecyltrimethylammonium bromide (HDTMA) (referred as HDTMA-Bent herein), a commonly used surfactant, to increase its adsorption potential. The influence of important experimental parameters, including initial aniline concentration, contact time, solution pH, and adsorbent dosage were studied to optimize the experimental conditions. The results showed that with the increase in adsorbent concentration or initial pH value of the solution, the aniline removal efficiency was also increased. The prepared adsorbents were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction (XRD) analysis. According to XRD analysis, the increase in the microscopic platelets of modified bentonite could be the reason of enhanced adsorption of aniline. The adsorption kinetics followed th...

Adsorptive removal of Cr(III) and Fe(III) from aqueous solution by chitosan/attapulgite composites: Equilibrium, thermodynamics and kinetics

Adsorption of Cr(III) and Fe(III) onto chitosan/attapulgite composites (CTS/ATP) was investigated with respect to pH, temperature, initial concentration and binary solution. Equilibrium data, at various temperatures, were described by the Langmuir, Freundlich isotherm models. The Freundlich isotherm model was fitted to the experimental data significantly better than the Langmuir isotherm. In a binary solution, the combined effect of adsorbing one metal ion in the presence of the other metal ion reduced the adsorption capacity of either metal ion. The kinetic data was well fitted to the intraparticle diffusion equation, which indicated that the three adsorption steps belonged to the pseudo-second-order adsorption process. Intraparticle diffusion increased with the increase in adsorbate concentration while film and pore diffusion decreased. The thermodynamics parameters (positive values of Δ H°, Δ S° and negative values of Δ G°) indicated the binding systems between CTS/ATP and adsorbate were endothermic, entropy gained and spontaneous in nature.

Competitive heavy metals adsorption on natural bed sediments of Jajrood River, Iran

The presence of heavy metal concentrations was examined in natural sediments from four sites along the Jajrood river in northeast of Tehran, the capital of Iran. Besides determination of elemental concentrations (Pb, Cu, Zn, Cd, Ni and Cr), X-ray fluorescence and X-ray diffraction tests were carried out to determine other chemical components in these adsorbents. Also the ability of sediments to adsorb these heavy metal ions from aqueous solutions was investigated. Results show that the extent of adsorption increases with increase in adsorbent concentration. The amount of adsorbed Pb, Cu and Zn in sediments was much greater than that of the other metals, and Cr was adsorbed much less than others. The adsorbabilities of sediments to heavy metals increased in the order of Pb > Cu > Zn > Cd > Ni > Cr. Based on the adsorption data, equilibrium isotherms were determined at selected areas to characterize the adsorption process. The adsorption data followed Freundlich and Langmuir isotherms in most cases. Correlation and cluster analysis was performed on heavy metals adsorption and sediment components at each site to evaluate main adsorbing compounds in sediments for each metal. Results demonstrated that heavy metals sorption is mostly related to load of organic matter in the Jajrood river sediments.

Adsorption of T-2 toxin by natural mineral adsorbents

The contamination of animal feed with mycotoxins represents a worldwide problem leading to economic losses in animal production. According to the Food and Agriculture Organization (FAO), 25% of the world's cereal grain production is contaminated with mycotoxins. The most common mycotoxins found in grains are the aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone and the ergopeptine alkaloids. Trichothecenes, constitute the largest group of Fusarium mycotoxins. Among others, T-2 toxin is the most acute toxic trichothecene. In this paper, adsorption of T-2 toxin by natural mineral adsorbents zeolite-clinop-tilolite and smectite minerals - bentonite and hectorite, at pH 3 was investigated. The highest adsorption index was achieved for hectorite (95%), while clinoptilolite and bentonite showed low adsorption index for T-2 toxin, 8% and 13%, respectively. Results of T-2 toxin adsorption on hectorite, at different amount of solid phase in suspension, and at pH 3, 7 and 9, showed that toxin adsorption indexes increased with increase of adsorbent concentration in suspension, at all investigated pH values. No significant differences in T-2 toxin adsorption by hectorite, at pH 3, 7 and 9 were observed.

Removal of estrone and 17 β-estradiol from water by adsorption

Endocrine disrupting chemicals (EDCs) are the focus of current environment concern, as they can cause adverse health effects in an intact organism, or its progeny, subsequent to endocrine function. The paper reports on the removal of estrone (E1) and 17 β-estradiol (E2) from water through the use of various adsorbents including granular activated carbon (GAC), chitin, chitosan, ion exchange resin and a carbonaceous adsorbent prepared from industrial waste. The results show that the kinetics of adsorption were adsorbent and compound-dependent, with equilibration being reached within 2 h for a waste-derived carbonaceous adsorbent to 71 h for an ion-exchange resin for E1, and within 7 h for the waste-derived carbonaceous adsorbent to 125 h for GAC for E2. Of all the adsorbents tested, the carbonaceous adsorbent showed the highest adsorption capacity, with a maximum adsorption constant of 87500 ml/g for E1 and 116000 ml/g for E2. The GAC also had a very high adsorption capacity for the two compounds, with a maximum adsorption constant of 9290 ml/g for E1 and 12200 ml/g for E2. The effects of some fundamental environmental parameters including adsorbent concentration, pH, salinity and the presence of humic acid and surfactant on adsorption were studied. The results show that adsorption capacity of activated carbon was decreased with an increase in adsorbent concentration and by the presence of surfactant and humic acid. The results have demonstrated excellent performance of a waste derived adsorbent in removing E1 and E2 from water, and indicated the potential of converting certain solid waste into useful adsorbents for pollution-control purposes.

Ampicillin adsorption by some antacids

In certain situations of peptic ulcers ampicillin has been co-administered with bismuth carbonate with an implication for adsorption of the ampicillin. To quantify this effect the kinetics and extent of adsorption of ampicillin by some commonly used antacids were measured; these are bismuth carbonate, magnesium trisilicate and aluminium hydroxide. The adsorption of ampicillin by bismuth carbonate followed the Langmuir adsorption isotherm, which suggests chemisorptions. It was characterized by a strong adsorption at a low adsorbate (ampicillin) concentration but the % adsorption decreased with increase in adsorbate concentration, which is a feature of a saturated monolayer adsorption. On the other hand, the adsorption by magnesium trisilicate and aluminium hydroxide followed the Freundlich adsorption isotherm characterized by a low adsorption at a low adsobate concentration but this increased slightly with increase in adsorbate concentration, suggesting a weak physical adsorption. The adsorption capacities (mg/g) of the adsorbate were 1.64 (bismuth carbonate) 0.04 (magnesium carbonate) and 0.03 (aluminium hydroxide). Bismuth carbonate thus gave by far the highest degree of adsorption. The conclusion is that the co-administration of ampicillin and bismuth carbonate in the treatment of certain peptic ulcers is erroneous.

Adsorption of 3‐ and 4‐benzoylpyridine on colloidal silver particles: a surface‐enhanced Raman scattering study

AbstractSurface‐enhanced Raman scattering (SERS) spectra of 3‐ and 4‐benzoylpyridine (BP) adsorbed on silver hydrosols were compared with the FTIR and normal Raman spectra in bulk and in solution. With a small fractional change in adsorbate concentration, the SER spectra of isomeric BPs show significant changes in their features, indicating different orientational changes of the different parts of the flexible molecule on the colloidal silver surface with adsorbate concentration. The appearance of a broad, long‐wavelength band in the absorption spectra of the silver sol due to solute‐induced coagulation of colloidal silver particles is found to be red shifted with increase in adsorbate concentration. The SER excitation profiles indicate that the resonance of the Raman excitation radiation with the new aggregation band contributes more to the SERS intensity than that with the original sol band. Copyright © 2004 John Wiley & Sons, Ltd.

Concentration-dependent surface-enhanced Raman scattering of 2-benzoylpyridine adsorbed on colloidal silver particles.

Surface-enhanced Raman scattering (SERS) of 2-benzoylpyridine (2-BP) adsorbed on silver hydrosols has been investigated. It has been observed that with a small change in the adsorbate concentration, the SER spectra of 2-BP show significant change in their features, indicating different orientational changes of the different part of the flexible molecule on the colloidal silver surface with adsorbate concentration. The time dependence of the SER spectra of the molecule has been explained in terms of aggregation of colloidal silver particles and co-adsorption and replacement kinetics of the adsorbed solute and solvent molecules on the silver surface. The broad long-wavelength band in the absorption spectra of the silver sol due to solute-induced coagulation of colloidal silver particles is found to be red-shifted with the increase in adsorbate concentration. The surface-enhanced Raman excitation profiles indicate that the resonance of the Raman excitation radiation with the new aggregation band contributes more to the SERS intensity than that with the original sol band.

Removal of mercury ions from aqueous solutions by composite of polyaniline with polystyrene

Radiotracer technique has been used to study the removal of Hg(II) ions from aqueous solutions by composite of polyaniline with polystyrene. This study reveals that the increase of adsorbent concentration (10 −8–10 −3 M) and temperature (293–333 K) enhances the removal of Hg(II) ions. Concentration-dependence data agree well with the Freundlich isotherm. Thermochemical data show that this process is endothermic in nature. The radiation stability of the composite was also investigated by exposing it to a 11.1-GBq (Ra–Be) source associated with γ dose of 1.72 Gy h −1. Irradiation has practically no effect on the adsorption capacity of the composite. Desorption experiments show that the process of adsorption of mercury ions is almost irreversible and chemisorptive in nature.

Conformation of confined alkanes: n-butane in zeolite Y

Configurational-bias Monte Carlo simulation of n-butane in NaY zeolite has been reported at different temperatures and loadings. In contrast to n-butane in silicalite, the gauche conformer population is always found to be higher in zeolite NaY than in pure fluid at the same density. Normally, an increase in adsorbate concentration in gases such as methane, rare gases, etc. leads to an increase in population near the cage centre. In contrast, we find that an increase in n-butane concentration gives rise to an increase in population near the periphery of the cage. Enhancement in gauche conformer population observed for NaY zeolite is attributed to the surface curvature of the α-cavity.